Data storage units are known in which data is stored on flexible magnetic discs, known as "floppy discs", and subsequently read from the discs. In the prior art drive units, the discs are inserted into the unit through a slot. The slot is then closed by a manually operated cover. The cover is coupled to a disc-shaped clamp which serves to clamp the floppy disc to a drive hub. The hub is rotatably driven to turn the disc. A read/write magnetic head is moved radially with respect to the turning disc, so that data may be written on tracks across the face of the disc, and also so that previously written data may be read from the disc.
The drive mechanism of the present invention is an improvement over the prior art floppy disc drive described above, in that the disc is automatically centered and clamped against the drive hub after the disc has been inserted into the slot, and without any need to close a cover or to perform any other manual operations.
An important feature of the floppy disc drive of the present invention is that it includes means for positively assuring that the inserted floppy disc will be properly centered about the axis of rotation of the drive hub, before it is clamped against the hub.
The particular embodiment of the invention to be described is also advantageous over the prior art floppy disc drives since it contains a dual drive mechanism which enables two discs to be driven at the same time, so that identical or different information can be simultaneously read from or written on the two discs. There are drive units in the prior art which have two heads which engage the opposite sides of a single disc which has information to be written on or read from both sides. However, such prior art apparatus has been found to produce excessive wear on the discs. The dual disc unit of the present invention is one in which only one side of each of two discs is scanned at any one time by the magnetic head, so that the problem of wear does not arise.